Formatting string( where string represents a session) into date format using moment js

Question

i have a variable value that is giving me the data as "Session between Jan 15 2022 4:00Am And Jan 15 2022 4:30Am", i want to format this date string into "Session between 15-01-2022 4:00Am And 15-01-2022 4:30Am".

Things i have tried:

//function to remove "session between and" so that the date can be parsed.
public removeUnwantedText(words : any){
        var cleanUpWords = ["Session","between","And"];
        var expStr = cleanUpWords.join("\\b|\\b");
        return words.replace(new RegExp(expStr, 'gi'), '').trim().replace(/ +/g, ' ');
    }
//calling the function and trying to format date string,where value="Session between Jan 15 2022 4:00Am And Jan 15 2022 4:30Am"

 console.log(moment( this.removeUnwantedText(value),"MMM DD YYYY h:mmA").format('[Session between] DD-MM-YYYY  h:mmA [And] DD-MM-YYYY  h:mmA'));

the console ouptut is : Session between 01/15/2022 4:00Am And 01/15/2022 4:00Am

but the required output is Session between 01/15/2022 4:00Am And 01/15/2022 4:30Am

Any kind of help and suggestions would be appreciated. Thanks in advance

The console output is correct because you're outputting the same date to both places. Maybe you need to split the string on `'And'` and then replace the dates separately? — evolutionxbox, Feb 03 '22 at 08:11

Chris Hamilton · Accepted Answer · 2022-02-03T14:26:47.683

Welcome Iaxmy!

You don't actually need moment for this. The Date object will accept Jan 15 2022 in the constructor. You can use a regex to extract and replace the old strings with the new ones.

  reformatString(string: string) {
    //Find the dates
    const matches = string.match(/[a-zA-Z]+ [0-9]+ [0-9]+/g);
    if (!matches) throw new Error('Failed to parse string');

    //Convert to new format
    const newStrings = matches.map((s) => {
      const date = new Date(s);
      const month = (date.getMonth() + 1).toString().padStart(2, '0');
      const day = date.getDate().toString().padStart(2, '0');
      const year = date.getFullYear();
      return month + '/' + day + '/' + year;
    });

    //Replace with new strings
    matches.forEach(
      (match, index) => (string = string.replace(match, newStrings[index]))
    );

    return string;
  }

The regex searches for: word, number, number, all separated by a space.

You can also change this line if you wanted the DD-MM-YYYY format.

return day + '-' + month + '-' + year;

Edit

As pointed out by RobG, new Date(string) is implementation dependent. So I suppose you should avoid and use an external library like moment instead. It actually condenses this answer quite a bit.

  reformatString(string: string) {
    //Find the dates
    const matches = string.match(/[a-zA-Z]+ [0-9]+ [0-9]+/g);
    if (!matches) throw new Error('Failed to parse string');

    //Convert to new format
    const newStrings = matches.map((s) => {
      return moment(s, 'MMM DD YYYY').format('MM/DD/YYYY');
    });

    //Replace with new strings
    matches.forEach(
      (match, index) => (string = string.replace(match, newStrings[index]))
    );

    return string;
  }

Stackblitz: https://stackblitz.com/edit/angular-ivy-mk8ifz?file=src/app/test/test.component.ts

The format of "Jan 15 2022" is not supported by ECMA-262 so parsing is implementation dependent, see [*Why does Date.parse give incorrect results?*](https://stackoverflow.com/questions/2587345/why-does-date-parse-give-incorrect-results) — RobG, Feb 03 '22 at 11:33
Thank you very much @Chris Hamilton for providing a better solution. I learned something new. — laxmy Narine, Feb 03 '22 at 11:43
Hey no problem, although RobG made a good point above. I updated my answer to avoid using the Date constructor. — Chris Hamilton, Feb 03 '22 at 11:58
thanks again @Chris Hamilton, that was the reason why I was using "moment()", but my code wasn't up to the mark. — laxmy Narine, Feb 03 '22 at 12:11

score 0 · Answer 2 · answered Feb 03 '22 at 12:06

As suggested by @evolutionxbox, I tried it out and it works like that. below is the final code I wrote :

//function to remove gibberish words so that the value in the description column can parse the date.
    public removeUnwantedText(words : any){
    let cleanUpWords = ["Session","between","And"];
    let expStr = cleanUpWords.join("\\b|\\b");
    return words.replace(new RegExp(expStr, 'gi'), '').trim().replace(/ +/g, ' ');
   }
 //splitting the description data with And as breakpoint and storing them separately
     let sessionDate = value.split('And');
     let sessionStart = sessionDate[0];
     let sessionEnd = sessionDate[1];

  //formatting the date string into DD-MM-YYYY hh:mm A format.
   let sStart = moment(this.removeUnwantedText(sessionStart),["MMM DD YYYY h:mmA"]).format('[Session between] DD-MM-YYYY  h:mmA');
   let sEnd = moment(this.removeUnwantedText(sessionEnd),["MMM DD YYYY h:mmA"]).format('[And] DD-MM-YYYY  h:mmA');
           
//concatenating both the results into one and returning the output.
       let res = sStart +' '+ sEnd; 
       console.log(res);

The console gives me the expected output.

Thanks to everyone who helped me.

Formatting string( where string represents a session) into date format using moment js

2 Answers2